In terms of personnel, the Steelers' most glaring weakness is defensive back. Their biggest strength is linebacker.

So naturally, in crucial defensive situations, the Steelers put as many defensive backs on the field as possible while using only one linebacker.

Such is the contradiction that is the Steelers' dime defense. Maybe they should call it the Canadian dime defense, because the exchange rate of trading three linebackers for two extra defensive backs and an additional defensive lineman ranks the Steelers last in the NFL in third-down defense.

Among those not playing in the dime is linebacker Kendrell Bell, ostensibly because his high ankle sprain is not yet 100 percent. Frankly, I don't believe that.

If Bell is healthy enough to play in the basic defense, he's healthy enough to play in the dime. Bell was originally slated to line up at defensive end in the dime, but Haggans has collected six sacks, and it's likely that Haggans' perceived excellence is keeping Bell off the dime.

Bill Cowher dislikes midseason change unless it's absolutely necessary. Bell wasn't available for most of the campaign's early going and Haggans has done well. Therefore the dime stays as is.

That, of course, is ludicrous. No matter how well Haggans is doing, he simply isn't as good as Bell, the NFL Defensive Rookie of the Year last season.

And no matter how well any individual is doing, it doesn't alter the fact that the Steelers' dime defense stinks. There's no good reason to keep things intact. Besides being responsible for the team ranking last in the NFL in third-down defense, the Steelers' dime took less than eight minutes to blow a 17-point lead against Atlanta this past Sunday.

In case you can't connect the dots, let me help: When the Steelers let Sunday's game slip away in the fourth quarter, Bell was barely on the field. He's not in the dime, remember?

Will the congregation please join me now in saying, "How the heck does that make sense?" Amen.

Bell is too talented to keep off the field on third down, on first down, on any down. With all due respect to Porter, Bell is the Steelers' best all-around defensive player.

Bell says that his afflicted ankle aches when he gets into a three-point stance, which he would have to do if he played defensive end in the dime. That's an easy problem to solve.

Instead of the dime, the Steelers should use a nickel formation on passing downs. Pull a defensive back and play Bell at linebacker along with Porter.

That gets the Steelers' most feared defensive player on the field at a position he's comfortable with. It also pulls a defensive back. I think the benefits of that should be obvious.

In theory, the Steelers would be less effective in pass coverage if they used the nickel. But, in actuality, once you allow the opposition to convert a handful of third-and-20s, you can't possibly be less effective in pass coverage. And anyway, Bell's speed, athleticism and instincts would make him no worse on cover duty than whichever defensive back the Steelers would yank.

In addition, Bell's versatility and aggressiveness would force the opposing quarterback to think more and would make every player in a different-colored jersey have his head on a swivel. The Steelers could blitz more, blitz different and blitz better if Bell were on the field for passing downs.

So, which defensive back to pull? Safety Lee Flowers jumps to mind because he's better at stopping the run than defending the pass. He's not a cover guy. But if one reason for switching to a nickel is to take advantage of Bell's aggressiveness, you don't want to bench your most aggressive defensive back.

My instinct says to sit a cornerback. Does it really matter which one? They're all terrible. You could put all those guys in a big canvas bag, beat it randomly with an ax handle, and whichever one got a fractured skull would deserve it. The Steelers' corners have been brutal.

Using a nickel formation would buck the NFL's current dime-happy trend, but so what? You've got to temper your system to maximize use of your best personnel. If you don't think Bell is among the Steelers' best players, you haven't been paying attention.

You need good coaching to win in the NFL. You need precise game plans, and you need to be proficient when it comes to situational substitutions.

But a coach's most basic duty is to identify his best players, then play them a lot. Kendrell Bell should be on the field as much as possible. Even if it means taking a nickel in exchange for a dime.

Mark Madden is the host of a talk show from 3 to 7 p.m. weekdays on WEAE-AM (1250).